It seems both russia and ukraine are claiming success with drone based attacks. I wonder how vulnerable radio controlled drones would be to blanket jamming. Is it possible to disrupt the radio signal between the controller and the drone, so that it crashes? There was a case some years ago, where an american drone was electronically hijacked by iran and stolen.
Drones as small as the ones ukraine uses, would be vulnerable to small arms fire.
S-400s would definitely be a prime target.
Try to hit a relatively silent target of 1 meter in diameter diving at 100 km/h towards you with small arms. I give you 10 tries, that is 9 more than real life, even at daytime.
As for the jamming, the details are not fully know, all I know is that the operator sets a target that may later change or skip completely. Jamming may be difficult, else drones would stand little chance. The active armour is something to consider yes, but modern antitank seem to have dual heads, like the javelin. Seem to do perfectly well.
We will see. War now is twitted more than an influencer's ass lately.